MMS (Magnetospheric Multiscale) is a Solar-Terrestrial Probe mission comprising four identically instrumented spin-stabilized spacecraft to discover the fundamental physics of magnetic reconnection using Earth's magnetosphere as a laboratory. The MMS spacecraft are being developed at NASA's Goddard Space Flight Center (GSFC) in Greenbelt, Maryland. GSFC is also responsible for the overall management of the MMS mission and mission operations. The mission is to be launched in October 2014 and will have an duration of two years (Prime Mission) + 6 months (launch, checkout, commissioning).